Electric motors are commonly used in a variety of applications. Such motors are electric machines that generate torque (or force, in the case of a linear motor) when supplied with an electric current. Electric motors may be used in a variety of applications. For example, teleoperative surgery involves the use of manipulator arms that move a medical instrument in a variety of spaces. The medical instrument at the end of a manipulator arm may be driven by an electric motor. For example, a stapler instrument may be attached to the distal end of a manipulator arm. A motor positioned proximal to the manipulator arm may be connected to the stapler through a system of drive-shafts and universal joints. Connecting the motor to such a system puts a load on the motor that causes the torque output of the motor to exhibit a torque ripple. The torque ripple creates an oscillation component in the torque output.
Sensor systems are used to safely and effectively operate the motor to provide the forces needed to accommodate, for example, a maximum tissue thickness for a stapler. For example, sensor systems may be used to ensure that the torque output does not exceed a predefined torque limit. When torque ripple occurs, the predefined maximum motor torque limit may be uniformly changed to accommodate the oscillation component of the torque output. However uniformly changing the maximum motor torque limit changes the tissue thickness that the stapler can routinely accommodate. Systems and methods are needed to allow for safe and effective operation of the motor while accommodating the forces needed by the stapler to accommodate maximum tissue thickness.